Vacuum control check valve



Jan. 8, 1946. c s 2,392,458 V VACUUM CONTROL CHECK VALVE Filed April 21,1944 AIR F/L TER v INVENTOR. BERT G. CARLSON JZTTORNEX Patented Jan. 8,1946 2,392,453, VACUUM CONTROL CHEGK VALVE Bert G. Carlson, Gates Mills,Ohio, assignor, by mesne assignments, to Jack & Heintz, Inc., Cleveland,Ohio, a corporation of Ohio Application April 21, 1944, Serial No.532,050

2 Claims.

This invention relates to vacuum control devices and has for one of itsprimary objects the provision of a vacuum control unit for use in thevacuum system of an automatic pilot including the gyro box, suction pumpand air filter which will effectively prevent excessive pressures beingbuilt up in the gyro box by the provision of a spring check valvebetween the air filter and the control unit leading to the gyro box toby-pass the same from the air filter line to the suction pump line andthe provision of a floating check valve in the unit which will closeupon the occurrence of backfire in the suction pump to prevent theingress of air, oil or foreign matter from the suction pump into thecontrol unit casing or into the gyro box.

With the foregoing and other objects in view theinvention resides in thecombination of parts and in the details of construction set forth in thefollowing specification and appended claims, certain embodiments thereofbeing illustrated in the accompanying drawing in which:

Figure l is a view in vertical section taken through the vacuum controlanddiagrammatically showing the vacuum system including the automaticpilot gyro box, suction pump and air filter;

Figure 2 is a view in perspective of the spring check valve; and

Figure 31s an enlarged plan view of the floating check valve.

Referring more particularly to the drawing, the conventional automaticpilot gyro box is indicated at I. As is conventional practice inpneumatic-hydraulic automatic pilots the gyro box is evacuated by asuction pump 2 to spin the gyro wheel and create the air force necessaryfor the functioning of the pneumatic parts of,the automatic pilotoperating system. Air from the outside is first drawn through an airfilter 3 and through a pipe 4 into chamber 5 of the control unit casing6 which chamber communicates through pipe I to the gyro box I to beevacuated. The outlet from the gyro box is through pipe 8 and intakeopening 9 into a chamber in the control unit casing 6 and out throughpassage II and pipe l2 to the suction pump 2.

In the chamber l3 intermediate chamber In and the outlet passage to pipeI2 is a floating check valve [4 which abuts the screw plug by reason ofsuction in pipe I 2 leaving passage for air from chamber In throughpassage I6 and chamber l4 and through outlet II to pipe l2. If, however,a backfire or back pressure occurs in the suction pump the floatingcheck valve I4 is forced to the left against the casing wall I! to closepassage 1 6 to prevent air from rushing back into chamber It! or to thegyro box. Moreover, inasmuch as the motor for running the suction pumpmay utilize oil the closing by check valve I 4 of passage It preventsthe ingress of any oil or foreign matter into the chamber [0 or the gyrobox.

Provision is also made against an excessive amount of air being drawn bythe suction pump through the air filter to the gyro box. This includes aspring check valve l8 normally maintained downwardly against its seat [9to close a passage '20 between passage 5 and chamber 10 by a compressioncoil spring 2| which also bears against a plate 22 carrying a stem 23screwthreaded in casing 6 so as to adjust the compression of spring 2|.

In the event that a predetermined undesirable amount of back pressuredevelops in chamber 5 the valve [8 becomes unseated against the actionof spring 2 I. The air thus flowing into chamber I0 is caught in thesuction flow of air and flows out through passages l6 and l I and pipeI2 to 25 the suction pump.

The two check valves l4 and I8 operate independently of each other andwithout interference to respectively prevent the sucking in of air, oilor foreign material into the gyro box upon backfiring of the suctionpump motor and prevent the building up of excessive pressure in. airfilter line being delivered to the gyro box.

I claim:

1. In combination in a vacuum system for evacuating and motivating theinstrumentalities of an automatic pilot gyro box, including a suctionpump and an air filter, a vacuum control unit between said air filterand gyro box and between said suction pump and gyro box, said controlunit including. a casing having a central chamber having an inlet fromthe gyro box line and an outlet port to the suction pump line, afloating check valve permitting flow at all times to said suction pumpline and operable upon occurrence of back pressure therein to close saidoutlet port to prevent transfer of back pressure into said centralchamber or gyro box, said casing also having a passage communicatingwith the gyro box and air filter lines and a by-pass between saidpassage and said central chamber, a spring check valve in said centralchamber for normally maintaining said passage closed and adapted to beopened upon the occurrence of excess pressure in said air filter line toby pass such pressure away from the gyro box line into said centralchamber and into the suction fiow'of the suction pump line.

air filter and gyro box and between and in communication with saidsuction pump and gyro box, said control unitcomprising a casing havinga.

sage communicating with the gyro box and air central chamber; a checkvalve permitting fiowj at all times to the suction pump line andoperable in response to back pressure therein to close flow from saidsuction pump line to said central chaml 7/ p 7' her and gyro box, saidcasing also having a pas filter lines and a by-pass between said passageand said central chamber, a check valve in said central chamber andadjustable spring means for normally maintaining said passage closed andadapted upon the occurrence of excess pressure in said air filter lineto by-pass such pressure away from the gyro box line and into saidcentral chamber and into the suction flow of the suction pump line, saidcheck valves being operable independently of each other withoutinterference.

BERT G. CARLSON.

